Covarient's larger cap is more useful than resilient for pve and most pvp. Typical dmg leaked to hull isn't going to kill you, and mostly fixes itself, especially for a carrier with high hull and large crew. There are certain pvp fits built around bypassing shield, but npcs won't have them.
Adapted MACO set is really for sci ships. The shield is very difficult to keep fully charged with a low shield modifier, and if you arent keeping it fully charged it is unused capacity that is being wasted.
So I guess Mark X should be fine if I don't really care about the minor increases.
It's fine, but the difference between X and XII is not unnoticeable. If you already have XI set, it may not be worth upgrading to XII. But if you've got nothing, it's better to just get the best as opposed to mk X.
The bigger gap is between resilient and covarient. There's a difference of around 2000 at mk XII level. You should really weight if the 5% bleedthrough is worth the cap difference for you. For most people, it's not. Like I said, under most situations, bleedthrough dmg fixes itself. People spend millions on field generators for less cap than that.